A variety of medical imaging technologies is available for producing images of the interior of the human body, for example for diagnostic purpose. Radiography (an imaging technique that uses electromagnetic radiation other than visible light, for example X-rays, to view the internal structure of an object such as the human body) is frequently used for this purpose, and fluoroscopy is an imaging technique used by physicians/radiologists to obtain real-time moving image of internal organs or structures of a patient (e.g., small bowel, colon, anorectum, or other parts of the gastrointestinal (GI) system, blood vessel, etc.) through the use of a fluoroscope. Such images are typically used during surgery, for example, in order to ensure that a stent or screw is inserted correctly.
It is also known that a contrast material may be introduced into the patient to help mark anatomy parts as part of a study using fluoroscopic imaging. The contrast material may reveal functioning of, for example, blood vessels or the GI tract. Known contrast materials may include, for example, barium in the form of barium sulfate (BaSO4), which may be administered orally or rectally for GI tract evaluation, and iodine in various proprietary forms. These contrast materials absorb or scatter significant amounts of x-ray radiation and may be used with real time imaging to demonstrate dynamic bodily processes, for example esophageal peristalsis. (Esophageal peristalsis refers to the contraction of muscles in the esophagus to push forward food and liquids through the esophagus to the stomach.
There are conventional imaging systems, one of which is described in U.S. Patent Publication No. 2009/0257554, that use a contrast material to visualize and display body organs or structures, for example during operation. Sensors are often positioned in a body organ (e.g., by using a catheter) to be imaged in order to measure and display physiological parameters (e.g., peristaltic pressure) that pertain to the visualized body organ. In order to interpret the measurements correctly, which is a prerequisite to useful analysis, each measurement has to be associated with the correct sensor and with the correct sensor's location in images of the radiographically imaged organ. However, as the contrast (radiopaque) material moves in the body organ, for example in the esophagus (e.g., during a patient swallowing), it may occlude or hide one or more sensors partly, entirely, completely or to some extent, and thus render sensors radiographically invisible/indiscernible. The level of invisibility of sensors depends, among other things, on the density and propagation pattern of the contrast material in the body organ. That is, sensors may be indiscernible in some images, partly or fully discernible in other images, and very, or faintly discernible in other images.